Native shrub and plant diversity mitigate plant invasion in eastern China's humid grasslands.

Question: Understanding the factors influencing plant invasions is essential for effective prevention and control actions. However, the relative importance of the biotic resistance, resource availability, and propagule pressures on invasive plants in fragmented grasslands of humid and semi‐humid regions remains unclear. Locations: Shandong Province, eastern coastal China. Method: This study is based on community composition and soil nutrient data from 42 grassland plots of 30 × 30 m surveyed between 2021 and 2022. In each plot, we sampled six sub‐plots of 2 × 2 m, totaling 24 m2. We used beta regressions and general linear models to examine the coverage, relative coverage and relative richness of invasive plants in relation to community structure (such as richness and coverage of native shrubs, species richness, phylogenetic diversity and functional traits of native herbaceous plant), macroclimate, soil nutrients and human activities. Partial regressions and Random Forest analyses were used to assess the relative importance of different predictors. Results: The coverage, relative coverage and relative richness of invasive plants decreased with the richness and coverage of shrubs, but increased with phylogenetic diversity of native herbaceous plant. Community structure factors, particularly shrub richness and coverage, exhibited higher relative importance on invasive‐plant performance compared to other variables. Conclusions: Our results indicate that diversity–invasibility relationships are sensitive to the choice of diversity index. Overall, native shrubs within the local community play a crucial role in buffering against the spread and establishment of invasive plants in humid grasslands, underscoring the significance of biotic resistance in plant invasion. [ABSTRACT FROM AUTHOR]